Nowadays, a lithography method is generally employed as a manufacturing method of semiconductor devices such as highly integrated LSIs. In the case where a semiconductor device is manufactured by this lithography method, in general, after forming an electrically conductive thin film such as metallic films operating as an electrically conductive wiring material or an interlayer insulating film such as a silicon oxide film for the purpose of achieving insulation between wirings on a substrate such as a silicon wafer, a photoresist is uniformly coated on the surface thereof to provide a photosensitive layer, which is then subjected to selective exposure and development treatment to form a desired resist pattern. Subsequently, the thin film in a lower layer part is subjected to a selective etching treatment through this resist pattern as a mask to form a desired resist pattern on the subject thin film. Then, a series of processes for completely removing this resist pattern are taken.
In recent years, in semiconductor devices, high integration is advanced, and the formation of a pattern of not more than 0.18 μm becomes necessary. Following the ultra-microfabrication of this processing size, a dry etching method has become the main current in the foregoing selective etching treatment. In the dry etching treatment, it is known that residues to be caused due to a dry etching gas, a resist, a film to be processed, a treatment member in a dry etching apparatus, etc. (the residues will be hereinafter referred to as “etching residues”) are formed in the surroundings of the formed pattern. In particular, when etching residues remain in the inside of a via hole and the surroundings thereof, non-preferable situations including high resistance and the generation of an electric short circuit are brought.
Organic amine based strippers composed of a mixed system of an alkanolamine and an organic solvent are disclosed as a cleaning solution for removing etching residues in a process for forming a metal wiring (see Patent Documents 1 and 2). However, in such a cleaning solution, in the case where after removing the resist and the like as well as etching residues, water washing is performed, the amine is dissociated due to the absorbed moisture to assume alkalinity, and it corrodes a metal film or the like. Therefore, a rinse solution requires an organic solvent such as alcohols, and there is involved a problem that burdens on the safety and environment are large.
Also, fluorine based cleaning solutions composed of a fluorine compound, an organic solvent, an anticorrosive and the like are used as a cleaning agent having higher ability to remove etching residues and a resist cured layer than the organic amine based stripper (see Patent Documents 3 and 4). However, in recent years, conditions for dry etching in the manufacturing process of semiconductor devices have become severe, and a resist is more likely denatured. Thus, it has become impossible to achieve complete removal with the foregoing fluorine based aqueous solution.
In these organic amine based cleaning solutions or
In these organic amine based cleaning solutions or fluorine based cleaning solutions containing a large amount of an organic solvent, in the semiconductor manufacturing process, burdens on the economy and environment such as safety measures and liquid-waste treatment are large, and excessive measures are needed. For that reason, an acid based cleaning agent which is an aqueous solution of an organic acid and a reducing agent is disclosed as a water-soluble cleaning solution (see Patent Document 5).
However, according to this water-soluble cleaning solution, it is impossible to completely remove firmly denatured etching residues. Also, since the reducing agent is consumed for the reduction of chemical components or components in air, not only the base-before date is short, but special custody is necessary for keeping the quality. Furthermore, since the water-soluble cleaning solution is a strong acid, special attention must be paid for the disposal, and it cannot be said that the burdens on the economy and environment are thoroughly reduced.
For these reasons, a cleaning solution capable of completely removing etching residues without damaging wiring raw materials and bringing little burdens on the safety and environment in the semiconductor manufacturing process is keenly demanded.
Patent Document 1: JP-A-62-49355
Patent Document 2: JP-A-64-42653
Patent Document 3: JP-A-7-201794
Patent Document 4: JP-A-11-67632
Patent Document 5: JP-A-2003-16730